It sounded so playful that many Californians wondered if he was just trying to win over one of his favorite cards, Gov. Greg Abbott of Texas. Others doubted that he was serious because that would mean he would adopt a donation enforcement system that he considered legally dubious. Seven months later, Mr. Newsom is not only poised to sign the bill on Friday, but he has leaned more than ever in his rhetoric against Republicans. He ran an ad this month in Florida attacking the state’s Republican governor, Ron DeSandis, a possible 2024 presidential contender. He has rebuked other states for banning abortions and has seized on the Supreme Court for its recent rulings that overturned Roe v. Wade and granted Americans a broad right to bear arms in public. While he has repeatedly insisted that he has no intention of running for the White House in 2024, Mr. Newsom’s actions sometimes seem to belie his statements. The Florida ad — a $105,000 spot worth more in free publicity — turned heads in national political circles. So did his visit to Washington this month and his remarks this spring that his fellow Democrats were too lukewarm on Republican moves. “I think he realizes that Democrats are hungry for a hero,” said Kim Nalder, a political science professor at California State University, Sacramento. “He’s building a profile as an alternative on the left to this aggressive policymaking that we’ve seen from Republicans in recent years.” No bill better encapsulates Mr. Newsom’s fight-with-fire-with-fire attitude than the bill that chooses an anti-abortion tactic in Texas to enforce California’s bans on assault weapons and phantom guns. Its aim is to bury those dealing in banned weapons in litigation. Awards of at least $10,000 per gun and legal fees will be offered to plaintiffs who successfully sue anyone who imports, distributes, manufactures, or sells assault weapons, .50 caliber rifles, guns without serial numbers, or parts that can be used to make firearms which are prohibited in California. “Nobody’s saying you can’t have a gun,” said state Sen. Bob Hertzberg, a veteran San Fernando Valley Democrat who was tapped by the governor to craft and veto the complex legislation. “We are simply saying that there is no constitutional right to an AR-15, a .50 caliber machine gun, or a serial numbered ghost gun.” On Friday, Mr. Newsom took out ads in three Texas newspapers rebuking Gov. Abbott, spending $30,000, according to campaign spokesman Nathan Click. The full-page spread replaces the word “abortion” with “gun violence” in a quote from Abbott about the Texas abortion law. He also calls the gun control legislation “California’s answer to the twisted Texas bill that rewarded doctors and patients.” Mr Abbott’s office did not immediately respond to a request for comment. The bill is the pinnacle of a sweeping package of gun restrictions signed by Mr. Newsom this month. The new laws include new limits on the advertising of firearms to minors. intensified restrictions on unregistered “ghost guns”; and a 10-year ban on firearms for those convicted of child abuse or elder abuse. “It’s time to stand up,” Mr. Newsom said in late June, after a court struck down a New York law similar to California’s that severely limited “public transportation” permits. He said at the time that California had anticipated the decision and was revising state law in ways that would offset “this radicalized and politicized Supreme Court.” He had 16 gun bills going to his desk, he said, and he planned to sign them all. The California laws come as mass shootings have intensified pressure for action on gun violence, as the death toll has risen this year from Buffalo to Uvalde, Texas. Last month, President Biden signed the most significant gun violence legislation to clear Congress in nearly three decades, expanding background checks for gun buyers under the age of 21 and making millions of dollars available for states to enact gun laws. the “red flag” that allow authorities to temporarily confiscate weapons from people deemed dangerous. But the congressional response, constrained by a powerful gun lobby and deep partisan polarization, is far from the comprehensive solutions many researchers believe are needed. And the 6-3 conservative majority on the Supreme Court has signaled a trend not only to preserve, but further expand gun rights. That left Democratic-led states to seek their own solutions. The inquiry has expanded beyond gun violence policies as court rulings have upended reproductive rights and jeopardized LGBTQ protections and other civil liberties. Increasingly, the charge from the left is being led by Mr. Newsom, who has had political capital to spare since last year when he crushed a Republican-led recall. Dan Schnur, a former Republican strategist who now teaches political science at the University of Southern California and the University of California, Berkeley, said the governor’s motives were easy to deduce: Mr. Newsom believes the “California way” is success and Using a national platform to call Republicans helps rally voters in the many media markets in his own vast state. Also, Mr. Schnoor said, “He’s going to run for president.” Mr. Newsom has said he has “below zero interest” in the White House. “But just being seen as a player on the national stage serves him well, even if he never runs,” Mr Schnur said. “Mario Cuomo has been playing this game for years.” California’s gun laws are among the strictest in America, helping the state achieve one of the lowest gun death rates in the country. In 2020, the state’s firearm death rate was about 40 percent lower than the national average, according to the Centers for Disease Control and Prevention, and the California Public Policy Institute has determined that Californians have about 25 percent fewer chances of mass shooting deaths, compared to residents of other states. California’s gun policies, however, have been strained as conservative federal judges, many appointed by the Trump administration, have taken an increasingly hard line on Second Amendment rights. California’s gun bounty law is expected to face legal challenges that could eventually land in the Supreme Court. The measure won’t go into effect until next year and includes a legal trigger that would automatically invalidate it if courts strike down its bases in Texas. The National Rifle Association and other gun advocates have argued that current state law already offers remedies for illegal activities by California firearms manufacturers and dealers. The same groups argued from the start that the measure’s bounty program could — and would — curtail the Second Amendment, and the American Civil Liberties Union echoed their concerns. “The problem with this bill is the same problem with the Texas anti-abortion law it emulates: it creates an end around the core function of the courts to ensure that constitutional rights are protected,” the ACLU said in a letter opposing the legislation of California. . The group also charged that the legislation would “escalate an ‘arms race’” in creative legal attacks on politically sensitive issues such as contraception, gender-affirming care and voting rights. A recent NRA legislative update said that on this and several other gun bills, they were “considering all available options, including litigation.” In the meantime, Mr. Hertzberg said, Democrats will use all available tools. “I don’t agree with the Supreme Court,” he said, “but if Texas is going to use this legal framework to harm women, then California is going to use it to save lives by taking illegal guns off the streets.”